Magnetic coupling



Nov. 7, 1939. G, NEUMANN MAGNETIC coUPLING Filed Sept. 28, 1935 'M Illl 15 Patented Nov. 7, 1939 c UNITED STATES PATENT oFElcE 2,118,641 MAGNETIC COUPLING Georg Neumann, Berlin, Germany Application September 28, 1935, Serial No. 42,658

In Germany October 5, 1934 This invention relates to a magnetic coupling lIt will thus be noted that it is possible, by or relay'and has particular reference to a magsuitable energizing of the two coils l0 and I4, netlc coupling for use in measuring, recording to control the amount of, friction between the and like instruments; disks I6, il, and the armature member I8 on the It is an object of the present invention toV pro one hand and between the disks i6, l'l and the 5 vide a magnetic coupling or relay which permits armature member le on the other hand so that, reciprocal movement of an associated armature, when the amounts of friction at It and i9 are under control of electrical currents acting upon not exactly similar, the fork 2li will be moved in coils forming part of the coupling. a direction depending on the irictional ratio and Another object of the invention is to produce the direction of rotation oi the shaft 3l. 10 a relay which is adapted to carry out controlling While my said novel magnetic relay may be or adjusting movements with an increased meused for a wide variety of diierent purposes oi chanical power under the control or" comparause, one application of the same whichvis repretively small electrical currents, more particusentative :for the usefulness of my relay will be larly fed from a measuring instrument or micro hereinafter described by Way of example. phone. Referring again to Fig. l, showing my novel With these and other objects in view, as may relay installed in a sound recording apparatus, become apparent from the within disclosures, it will be seen that a microphone i is exposed to the invention consists not only in the structures the sound the intensity ci which is to be recorded, herein pointed out and illustrated by the drawand, together with the associated amplifier 2, il@ ings, but includes further structures coming makes up means for transforming sound into elec-v vJithin/tiie scope or what hereinafter may be trical output. A potentiometer 3 the resistance claimed. A value of which along its length is preferably pro- The character of the invention, however, may vided to grow in accordance with a logarithmic be best understood by reference to certain oi, its curve, receives its input current from said sound 25 structural forms, as illustra'd by the accomtransforming means', and is provided with a slidpanying drawing in whiching contact or movable member Il. One end oi Fig. l is a diagrammatic View snowing an em= the potentiometer 3 and the sliding contact l bodiment o my novel coupling, in a iront ele= are connected to the input terminals of a second Vatn; aS imbued 530 2 501m@ YGCOTdi-lg lllif ampliier 5, the output terminals of which are 30 ratus. connected to the grid and the cathode l o2 the Fig. 2 is a side view oi the magi-165i@ Cilupiing electron valve 8 acting as an audion valve, by' Shown in 'irneans of tne condensers and resistances neces- Figs. 3 to 6 are modied circuit diagrams for sary the audios. circuit. In the anode cir energizing mi 110V@ magnetic @Oilill cuit oi the valve S there is inserted, in series to 35 Figs. 'l' and 8 are characteristic curves ci ther me mamie 19g-@tem g, the Winding fommg pari, mionic valves for use in connection with my novel of the above desu-bed magneti@ Couphng @ne magnetic Coupnterminal of the winding lil is connected to the Similar @ference mumeadls denote Sm'ila' cathode d oi the audion 8, while the other tern Parts m the dlfieen" Mews' ininal thereof is connected to the grid il or a t 'efergn l?? t hedrglg .ltnvleaigersedr' second electron valve, in the anode circuit of l tiat e rnasgneicn ray caompriss two diks iii Wmo?? th? eond Wmdpg M. Of the magnetic and il of a, suitable magnetisable or magnetic Coupling mberpolm'ed m sernes Wlth an anode material mounted on a common shaft @l which battery ai" The thofes 0i the tf'wo Valves g3 is rotated by means not shown in the drawing. anadm ifi cnbefo tli; btesul m r a The dlsks n@ and H are magnetlcguy Intercom A pen or stylus 2|] mounted on the fork 2e draws nected by a central part 22 and adapted to be o I energized by stationary coils lil and ld surrotmd- L Curve fm a' pap@ 55m? or the me@ Tunning We? ing the upper and lower portions of the disk it, 'me mers 23 and 2Q which Curve 'Tepesents 5e respectively. Armature members gg and gg) of a the sound intensity values received by the microfork 2t engage the opposite portions of disks l@ P11021@- ''he drilling arrangement OI' 'the papel and I1, under slight resilient friction, thus :make strip is not shown, for the sake of clearness.

ing up two closed magnetic circuits il, 22, it, le The function of my novel magnetic relay will and il. 22, i6, le, respectively. now be described in connection with the oper- 55 tions created by the coils ation of the said sound recording device follows:

If no sound acts on the microphone I, the sliding contact 4 and the pen 2| may for instance be in their left hand end position, so that the input terminals of the amplifier 5 are in connection with the end terminals of the potentiometer. In this working condition the maximum anode current flows in the anode circuit of the valve 8, which energises the coil I0 and consequently magnetises that part of the disc I6 which happens to be the bottom part at the time. The potential drop obtaining in the coil I0 is impressed as a negative grid bias on the valve I2, so that the anode circuit of. this valve and consequently also the excitation coil |4 is dead. By reason of this the rotary discs I8 and I'I of the magnetic coupling, which are magnetised in their bottom parts only, tend to im-' part a movement to the fork 2Il in a left hand direction, while the fork cannot carry out this movement as the sliding contact 4 and the pen 2| as mentioned above are already in their left hand end position, defined by a stop or the like, as indicated at 38.

Now if a sound of a definite intensity impinges on the microphone and consequently generates currents in the microphone and thus a potential on the potentiometer, then the grid 8 becomes charged through the sliding contact 4 and the amplifier 5, which causes the anode current of the valve 8 to drop, whereby the excitation of the coil I0 is weakened and the potential of the grid of the second valve |2 altered, so that now a current arises in the anode circuit of this valve, which energises the coil I4 and thereby magnetises the top part of the discs I8 and I'I. Since the magnetisation of the lower disc parts is thus decreased and that of the top parts increased, a push in the right hand direction is exerted on the fork 20 which lasts for so long until, by reason of. the action hereafter described, the magnetisa- III and I4 balance each other in their action on the legs I8 and I8. By reason of the push to the right exerted on the fork 20 the sliding contact 4 and the pen 2| are pulled to the right together with the fork. By this movement the contact 4 taps on' a constantly dropping potential on the potentiometer 8, so that the biasing potential on the grid 8 changes again in the opposite sense, and consequently the anode current ilowing through the coil I8 rises again. But at the same time the bias potential of the grid |I is also changed again. Consequently the anode current of the second valve. I2 and with it the energising current of the coil I4 is again weakened, and these changes continue for so long until the currents flowing in the coils I0 and I4 balance each other in their actions on the fork 20', and the sliding contact 4 and the pen 2| assume their positions corresponding to the sound intensity, around which they execute only small pendulous movements as long as the sound intensity remains unaltered. If the strength of the sound acting on the microphone decreases again, then the anode current in the anode circuit of the valve 8 rises so that the excitation of the coil III is strengthened. Simultaneously the anode current of the valve I2 drops and with it the energising current of the coil 'I'his causes a push towardsthe left to be exerted on the fork so that it is moved to the left-together with the sliding contact 4 and the pen 2|, into the position corresponding to the now obtaining sound strength, which position will coincide with the lett end position if a predetermined minimum or zero sound volume acts upon the microphone.

Each time when the sliding contact 4 and the pen 2l are in positions corresponding to the sound strength at the time, the forces exerted by the coils I 0 and |4 on the fork 20 neutralize each other. magnetic coupling and its excitation coils, this will be the case, when the same amount of current flows in both coils. When the number ot turns of the coils are diierent then the equilibrium is obtained at that current proportion which gives the same number of ampere turns. It is evident that in each of the fork 20 a quite definite proportion of current strengths reign in the anode circuits of the valves 8 and I2, and as the grid bias potential of the valve I2 is controlled only from'the anode current circuit of the valve 8, thh proportion between the anode currents only occurs at a quite definite value of the biasing potential of With a symmetrical design oi' the position of equilibrium the grid 8, that is to say at a quite definite value ot the input potential of the amplifier 5 tapped oil' by the sliding contact 4.

It is therefore evident that the sliding contact 4 always takes up such a position that the input potential of the amplifier 5 and the current and potential proportions of the circuit elements lnterpolated after it have in the constant condition the same value.

Figures 3 to 5 show a few further circuits for the excitation of the coils for the magnetic coupling. In the circuit according to Figure 3 the coil I8 is interpolated in the anode circuit of the first valve 8 in series with the anode battery 8 which is common to both the valves. as is also a resistance 28. The grid II of the second valve I2 is connected through a resistance 21 with a sliding contact 28 with which a source of electricity, such as for instance a battery 28 is connected in parallel, to a middle tapping point between the coil III and the anode of the first valve 8. Theexcitation coil 4 is interpolated between the anode of the second valve I2 and an intermediate point between the exciting coil I8 and the battery 9. In principle the functioning of this circuit is similar to that of Figure 1.. The sliding contact 28 is so adjusted, that no anode current ows in the second valve I2 when the first valve carries its full anode current. But as soon as the anode current of the first valve drops and thereby causes a decrease of the excitation of the coil III the bias potential of the grid I is altered so that an anode current begins to flow in the second valve I2, which excites the coil I4.

Figure 4 shows a circuit with only one valve 8 in the anode circuit of which the excitation coils III and I4, the anode battery 9 and a resistance 28 are connected in series. A further source of electricity (battery III) and a resistance 3| are connected in parallel to the second excitation coil I4. The potentials of the batteries and the resistances 26 and 3| are so chosen that when the full anode current ows in the valve 8 the coil I4 is without current. As is evident the coil I4 gets so much more current, the greater the anode current of the valve 8 is and the further the current in the coil I8 drops.

In the circuit according to Figure 5 there is also only one valve, but a double grid valve 82 is used, the coil III is in the anode circuit of the valve in series with the anode battery 8 and the resistance 28. The coil I4 is in circuit with the filament screening grid of the valve and is connected at a tapping point between the coil I and the battery 9. If a full anode current ows in the valve 32, i. e. if the coil I9 is at its maximum excitation, the current in the circuit of the filament screening grid is small, i. e. the coil i4 is only a little excited. When the anode current and the excitation current of the coil Ill drops then the current in the filament screening grid and the coil I4 rises.

In the circuit according to Figure 6 which is specially suitable for connection to the mains, the rectification does not occur in the final stage, but in an intermediate stage, two amplifying valves being provided behind the rectifying valve, the excitation coils being interpolated in the circuit of the amplifying valves in such a manner, that when the excitation current of one of the coils drops the current of the other rises. The amplifier is shown here as an amplifying valve, the output terminals of which are connected to the cathode and the grid of a rectifying Valve 33, which works with anode current rectification or anode bend rectification. A heating transformer 35 with its secondary winding tapped at the middle is used as a source for the cathode heating current, whilst the anode potentials for the individual valves are supplied by the terminals marked 150 V and 200 V, which in their turn are fed from the member connecting the apparatus to the mains or power supply. The terminals for 200 volts which lie in the anode circuit of the amplifying valve 5 are bridged over by a subdivided resistance 34 from the tappings of which the anode potential for the valve 5 and the grid biasing potentials for the rectifying valve 33 and also for the second nal valve are taken. In the anode circuit of the rectifying valve 33 there is interpolated a subdivided resistance 36, the tap of which is connected with the middle point of the heating transformer 35. The portions of the resistance 36 which are bridged over by the condensers 31, lie in the grid circuits of the amplifying valves 38 and 39, of which the iirst, 3B, works without any grid bias, whilst the second valve 39 has thereby a negative grid bias imparted to it, due to the fact that the corresponding part of the resistance 36 'is not connected direct, but through a suitably chosen part vof the potential dividing resistance 34, to the grid of the valve 39. The excitation coils I0 and I4 are interpolated in the anode circuits 38 and 39. In this case the anode currents supplied by the amplifying valve 5 are rectified by the valve 33 and amplified by the valves 38 and 39. By reason of the circuit of the valves 38 and 39 shown and their functioning with or without grid bias a similar result as that obtained with the circuit according to Figure 3 is attained, i. e. that the coil I4 is less excited when the coil lil is highly excited, and

Vice Versa.

According to the circuit diagrams shown in Figures 1 and 3 to 5, the valve 8 works in a rectifying circuit, the grid being however somewhat at a negative potential by reason of the battery in series with the resistance in the grid circuit. This is brought about for the purpose of eiecting a starting of the grid current only, when the positive wave half of the potential impressed on the grid exceeds a`certain value, so that the anode current has a non-linear, characteristic curve or increasing value relatively to the impressed potential. Figure 7 shows the diagram of this circuit, in which Ja designates the anode cur- A rent and Jg the grid current. As can be seen, the

, working point A is somewhat displaced by the negative grid bias potential.

Instead of working with an audion circuit it would also be possible, in Figures l and 3-5 to work with anode current rectification, similar to the circuit shown in Figure 6. But in such a case it is preferable to use a greater grid bias potential than usual, so that the working point A (Figure 8) lies far beyond the beginning of the anode current line Ja, in o rder to ensure that a nonlinear increase of the direct current component of the anode current follows a non-linear charactertistic curve.

What I claim is:-

1. A magnetic coupling comprising a constantly driven member including two rotating discs, two stationary exciting coils surrounding opposite portions of only one of said discs and adapted for variable and simultaneous energization, and a movable forked armature the legs of which engage on opposite sides of said discs so as to be controlled in accordance with the energization of said coils.

2. A magnetic coupling comprising a rotatable member including two rotating discs, stationary exciting coils associated with only one of said discs and adapted to be variously energized, and a forked armature engaging the peripheries of said discs for movements in accordance with the energization of said coils.

3. A magnetic coupling comprising a rotatable member including two rotating discs, stationary exciting coils associated with opposite portions of only one of said discs and adapted to be variously energized, and a reciprocatory armature having portions engaging on opposite sides of said discs and reciprocated thereby in accordance with the energization of said coils.

GEORG NEUMANN. 

